Steer axle suspension

ABSTRACT

A suspension ( 14 ) for coupling a steer axle assembly ( 12 ) to a vehicle frame ( 10 ) is provided that provides lateral stability to the steer axle assembly, increased roll stability for the vehicle and a reduction in axle wind-up during brakingcall without interfering with vertical displacement of the axle assembly. The suspension includes leaf springs ( 44 ) disposed on opposite sides of the vehicle, each of which is coupled to the vehicle frame at first and second ends ( 64, 66 ) and to an axle beam ( 28 ) intermediate the first and second ends. The suspension also includes first and second arms ( 50, 150 ), each of which is pivotally coupled to the axle beam at a first end ( 70, 170 ) and to the vehicle frame at a second end ( 68, 168 ) proximate one of the ends of a corresponding leaf spring. The suspension may further include a torsion bar ( 52 ) extending between and coupled to the first and second arms.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to vehicle suspensions and, in particular, to afront suspension for coupling a steer axle assembly to a vehicle frame.

2. Discussion of Related Art

A conventional vehicle includes a vehicle frame having a pair oflongitudinally extending frame rails that support the vehicle engine andbody. The frame is supported on a plurality of ground-engaging wheelsthat are disposed at opposite ends of a plurality of axles. The vehiclemay contain, for example, a steer axle on which the wheels are steerableby the vehicle operator and a drive axle whose wheels are driven by thevehicle engine. Each of the axles are coupled to the vehicle framethrough a suspension that dampens movements transmitted between thewheels and the vehicle frame.

One conventional suspension includes leaf springs disposed on oppositesides of a vehicle with each leaf spring coupled to the vehicle frame atfirst and second ends and to an axle beam intermediate the first andsecond ends. This conventional suspension has several disadvantages.During braking, movement of the axle causes the leaf springs to wind upproducing a caster change in the axle and a reduction in steeringstability. This problem is expected to become greater as mandatoryvehicle braking distances are reduced and, consequently, vehicle brakingloads increased. Conventional vehicle suspensions must also account forlateral movement of an axle and offer a degree of lateral stability aswell as roll stiffness to the vehicle. These objectives are sometimesachieved by using a track or stabilizer bar coupled between the frameand a component of the axle or suspension. These conventionalsuspensions, however, can interfere with vertical motion of the axle andcreate additional stress on some suspension components such as theabove-mentioned leaf springs.

The inventors herein have recognized a need for a suspension forcoupling a steer axle assembly to a vehicle frame that will minimizeand/or eliminate one or more of the above-identified deficiencies.

SUMMARY OF THE INVENTION

The present invention provides a suspension for coupling a steer axleassembly to a vehicle frame having first and second longitudinal framerails.

A suspension in accordance with the present invention includes a firstleaf spring coupled to the vehicle frame at first and second ends and toan axle beam of the steer axle assembly intermediate the first andsecond ends The suspension further includes a first arm pivotallycoupled to the axle beam at a first end and to the vehicle frame at asecond end proximate one of the first and second ends of the first leafspring. The suspension also includes a second leaf spring coupled to thevehicle frame at first and second ends and to an axle beam of the steeraxle assembly intermediate the first and second ends, the second leafspring disposed on an opposite side of the vehicle frame from the firstleaf spring. The suspension further includes a second arm pivotallycoupled to the axle beam at a first end and to the vehicle frame at asecond end proximate one of the first and second ends of the second leafspring. In one embodiment of the invention, the first and second armsare disposed on a forward side of the axle beam relative to thedirection of vehicle travel. In another embodiment of the invention, thefirst and second arms are disposed on a rearward side of the axle beamrelative to the direction of vehicle travel. Various embodiments of theinvention may also include a torsion bar extending between and coupledto the first and second arms.

A suspension in accordance with the present invention is advantageous.The suspension arms reduce axle wind-up during braking by transferringsome of the braking loads into the vehicle frame that would otherwisetravel into the leaf springs. The location and mounting of the torsionbar in some embodiments of the invention can also be used to reduce axlewind-up during braking and to provide lateral stability and rollstiffness without interfering with the vertical motion of the axle beamthereby reducing stress on the leaf springs in the suspension.

These and other advantages of this invention will become apparent to oneskilled in the art from the following detailed description and theaccompanying drawings illustrating features of this invention by way ofexample.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1-3 are perspective views illustrating a portion of a vehicleincorporating a suspension in accordance with one embodiment of thepresent invention for coupling a steer axle assembly to a frame of thevehicle.

FIGS. 4-6 are perspective views illustrating a portion of a vehicleincorporating a suspension in accordance with another embodiment of thepresent invention for coupling a steer axle assembly to a frame of thevehicle.

FIGS. 7-8 are perspective views of components of the suspensionillustrated in FIGS. 4-6.

FIGS. 9-10 are perspective views of a portion of the suspensionillustrated in FIGS. 4-6.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

Referring now to the drawings wherein like reference numerals are usedto identify identical components in the various views, FIGS. 1 and 2illustrate a vehicle frame 10 having a steer axle assembly 12 coupledthereto by a suspension 14 in accordance with the present invention. Inthe illustrated embodiment, frame 10 and steer axle assembly 12 areadapted for use with a heavy truck. It should be understood, however,that the present invention may find application on a wide variety ofvehicles.

Frame 10 is provided to support an engine (not shown), cab (not shown)and other components of a heavy truck. Frame 10 is conventional in theart and may be made from conventional metals and metal alloys such assteel. Frame 10 includes a pair of longitudinal rails 16, 18 extendingin the direction of vehicle travel and in the longitudinal direction ofthe vehicle. Frame 10 may also include a plurality of cross-members (notshown) extending transversely between rails 16, 18 and a plurality ofmounting brackets including brackets 20, 22, 24, 26.

Rails 16, 18 are provided to secure and align a cab on frame 10 and areconventional in the art. Rails 16, 18 are generally C-shaped incross-section and open toward one another. Rails 16, 18 may include aplurality of apertures configured to receive bolts, screws, or otherfasteners used to secure cross members (not shown), mounting brackets20, 22, 24, 26 and other vehicle components. The cross-members areprovided to connect rails 16, 18 and are conventional in the art. Thecross-members may also support various vehicle components including thecab and the vehicle engine

Mounting brackets 20, 22, 24, 26 are provided to couple components ofsuspension 14 to frame 10 and are coupled to frame 10 using conventionalfasteners such as screws, bolts, welds, or adhesives. Although onlybrackets 20, 22, 24, 26 coupled to rail 16 are illustrated in thefigures, it should be understood that substantially similar brackets maybe found on the opposite of the vehicle coupled to rail 18. It shouldalso be understood that the size, shape, and configuration of brackets20, 22, 24, 26 will vary depending upon design requirements andparameters associated with frame 10, steer axle assembly 12, andsuspension 14 and that variations may be made to brackets 20, 22, 24, 26without departing from the scope of the present invention.

Bracket 20 is disposed on an outboard side of rail 16 and may be coupledto rail 16 by one more conventional fasteners. Bracket 20 includes a pinproximate its lowermost end for a purpose described hereinbelow.

Bracket 22 may be coupled to rail 16 using conventional fasteners suchas welds. Bracket 22 includes a circular plate that defines a springseat for a purpose described hereinbelow.

Bracket 24 is coupled to rail 16 using conventional fasteners andextends longitudinally forward from the forward end of rail 16. Across-member is coupled to bracket 24 and a corresponding bracketmounted to rail 18 for use in supporting a vehicle engine. Bracket 24also defines a pair of downwardly extending spaced ears having alignedapertures for a purpose described hereinbelow.

Bracket 26 is coupled to bracket 24 and is suspended below bracket 24 ata forward end of bracket 24. Bracket 26 also defines a pair ofrearwardly extending spaced ears having aligned apertures for a purposedescribed hereinbelow.

Steer axle assembly 12 supports one or more steerable wheels (not shown)disposed on either side of the vehicle. Assembly 12 may include an axlebeam 28, kingpins (not shown) and steering knuckles 30 (one of which isshown in FIGS. 4-6).

Axle beam 28 supports wheels (not shown) disposed proximate either endof beam 28. Beam 28 may be made from conventional metals and metalalloys such as steel and may be forged or fabricated. Beam 28 extendstransverse to rails 16, 18 and each end of beam 28 defines a bore thatextends generally vertically and substantially perpendicular to thelongitudinal axis of beam 28. Each bore is configured to receive acorresponding kingpin.

The kingpins are provided to couple knuckles 30 to beam 28. The kingpinsmay be made from steel or other conventional metals and metal alloys.Each kingpin may be fixed against rotation within a corresponding boreof axle beam 28 using one or more drawkeys as is conventional in theart. The kingpins are generally circular.

Referring to FIGS. 4-6, knuckles 30 are conventional in the art and areprovided for mounting one or more wheels (not shown) of the vehicle andfor connecting assembly 12 and a vehicle steering assembly. Knuckles 30may be made from conventional metals such as aluminum and metal alloyssuch as steel and may be forged or fabricated. Each knuckle 30 mayinclude a body that defines one or more coaxial bore sized to receive acorresponding kingpin and bearings or a bushing surrounding the kingpinto allow the knuckles 30 to rotate relative to the kingpins. Eachknuckle 30 may include a tie rod arm 32 and one knuckle 30 may furtherinclude a steering arm 34 as is conventional in the art. Each knuckle 30may also include a brake mounting plate 36 and a spindle 38 (which maybe integral with the knuckle body or coupled thereto) on which wheelbearings (not shown) and one or more wheels (not shown) are mounted.

It should be understood that the steer axle assembly 12 described andillustrated in is exemplary only. The inventive suspension 14 claimedherein may find use on a wide variety of steer axle assemblies. In thesteer axle assembly 14 of FIGS. 1-3, axle beam 28 is a conventionalI-beam with a gooseneck configuration at either end. Further, eachknuckle 30 is a conventional yoke defining coaxial bores on either sideof beam 28 for receiving kingpins. Axle beam 28 may alternatively betubular and/or relatively straight while each of knuckles 30 define asingle knuckle boss as described in greater detail in commonly assignedU.S. Pat. No. 6,499,752, the entire disclosure of which is incorporatedherein by reference.

A steering assembly (not shown) is provided to enable the vehicleoperator to turn the wheels (not shown) supported on knuckles 30. Thesteering assembly is conventional in the art and may include a steeringgear (not shown), a crank (not shown) coupled to the steering gear, adrag-link extending between the crank and steering arm 34 of knuckle 30and a tie rod 40 extending between tie-rod arms 32 of knuckles 30. Thecrank rotates responsive to an output shaft extending from the steeringgear and causes corresponding movement in the drag link, steeringknuckles 30 and tie-rod 40.

Referring again to FIGS. 1-3, a suspension 14 in accordance with oneembodiment of the present invention will be described. Suspension 14couples steer axle assembly 12 to frame 10. Suspension 14 may includemounting brackets 42, leaf springs 44, air springs 46, shock absorbers48, mounting arms 50, and a torsion bar 52. Although only one side ofthe vehicle and suspension 14 are illustrated in FIGS. 1-3, it should beunderstood that like components for suspension 14 may be found on theopposite side of the vehicle.

Mounting brackets 42 provide a means for mounting one or more suspensioncomponents of suspension 14 to axle beam 28 for use in dampeningmovements between axle assembly 12 and frame 10. Brackets 42 aregenerally rectangular in shape. Each bracket 42 may define multiplegrooves 54 in an upper face 56 of the plate that extend transverse tothe longitudinal direction of the vehicle and substantially parallel tothe longitudinal direction of axle beam 28. Each groove 54 may terminateat either end in a bore that extends vertically through bracket 42.Grooves 54 are configured to receive conventional U-bolts 58 that extendthrough the bores in bracket 42 and into corresponding bores on beam 28to coupled bracket 42 to beam 28. Although each bracket contains twogrooves 54 each configured to receive a U-bolt 58, it should beunderstood that the number of grooves 54 and U-bolts 58 may vary. Eachbracket 42 may further define a pair of rearwardly extending spaced ears60, 62 having coaxial apertures. Ears 60, 62 are sized to receive oneeye of a shock absorber 48 with the apertures in ears 60, 62 receiving apin that extends through the eyelet of shock absorber 48. The upper face56 of bracket 42 defines a spring seat configured to receive spring 46and opposing the spring seat formed in mounting bracket 22.

Leaf springs 44 are provided to dampen movement and vibration betweenframe 10 and steer axle assembly 12. Leaf springs 44 also providelateral support to the steer axle assembly 12 by transferring lateralloads from the axle beam 28 into mounting brackets 20, 24 of frame 10.Springs 44 are conventional in the art. Each spring 44 extendssubstantially parallel to rails 16, 18 in the longitudinal direction ofthe vehicle and is coupled to frame 10 at forward and rearward ends 64,66 and to beam 28 of steer axle assembly 12 intermediate the forward andrearward ends 64, 66. The forward end 64 is pivotally coupled to bracket24 and disposed about a pivot axis between the downwardly extendingspaced ears at the forward end of bracket 24. The rearward end 66 iscoupled to a conventional shackle 67 which is in turn mounted on the pinextending from bracket 20. End 66 is also disposed about a pivot axis.Leaf spring 44 is coupled to beam 28 intermediate ends 64, 66 of leafspring by bracket 42. In particular, leaf spring 44 is disposed betweenor sandwiched between bracket 42 and beam 28, extending through theU-bolts 58 that couple bracket 42 to beam 28. In the illustratedembodiment, each side of the vehicle includes a single leaf spring 44.The use of a single leaf spring in combination with spring 46 on eitherside of the vehicle is advantageous as compared to conventional multipleleaf spring suspensions. In particular, the illustrated suspension has alower vertical spring rate that provides a softer ride for passengersand cargo.

Springs 46 and shock absorbers 48 are provided to dampen movementsbetween steer axle assembly 12 and frame 10. Springs 46 also absorb aportion of the vertical loads. Springs 46 are conventional in the artand may comprise an air spring. It should be understood, however, thatmechanical springs could alternately be used. Springs 46 are disposedbetween axle beam 28 and frame rails 16, 18. In particular, springs 46are supported on mounting brackets 42 between opposed spring seatsdefined by bracket 22 frame 10 and bracket 42 of suspension 14,respectively. Shock absorbers 48 are also conventional in the art. Shockabsorbers 48 are coupled at a first end to mounting brackets 42 and at asecond end to frame rails 16, 18. Shock absorbers 48 may include eyes ateach end configured to receive rod or tubes extending outboard fromrails 16, 18 and between the spaced ears 60, 62 of brackets 42.

Arms 50 provide a means for mounting torsion bar 52 to the vehicle. Arms50 also reduce axle wind-up during braking by transferring some of thebraking loads into frame 10 that would otherwise travel into leafsprings 44. Each arm 50 is disposed on a forward side of axle beam 28relative to the direction of vehicle travel. Each arm 50 extendsgenerally parallel to the longitudinal direction of the vehicle. Eacharm 50 is pivotally coupled to frame 10 and beam 28 at its forward andrearward ends 68, 70, respectively, with end 68 coupled to frame 10proximate the forward end of leaf spring 44 and about a pivot axis thatis substantially parallel to the pivot axis of the forward end of leafspring 44. End 68 of arm 50 is pivotally coupled to bracket 26 of frame10 in the illustrated embodiment using a conventional fastener and isreceived between the downwardly extending spaced ears of bracket 26. End70 of arm 50 is pivotally coupled to a mounting bracket 72 affixed toaxle beam 28 on the forward side of axle beam 28. Bracket 72 defines apair of forwardly and downwardly extending spaced ears sized to receiveend 70 of arm 50 and defining coaxial apertures configured to receive aconventional fastener. Each end 68, 70 may include a conventionalbushing or other means for enable relative rotation of arm 50 relativeto brackets 26, 72. Ends 68, 70 of arm 50 are both located below leafspring 44 in the illustrated embodiment. End 68 of arm 50 is alsovertically higher than end 70 of arm 50. Arm 50 further defines anaperture 74 intermediate ends 68, 70 of arm 50 configured to receive onelongitudinal end of torsion bar 52. As shown in FIGS. 1-3, arm 50 may bewidest at its connection points ends 68, 70 and aperture 74 to providesufficient strength to arm 50 while minimizing the weight of arm 50.

Torsion bar 52 is provided to increase the lateral stability and rollstiffness of the vehicle and to reduce axle wind-up during braking. Bar52 is disposed on a forward side of axle beam 28 and extendssubstantially parallel to beam 28, transverse to the longitudinaldirection of the vehicle. Bar 52 extends between and is coupled to arms50 on either side of the vehicle. Bar 52 is received within apertures 74of arms 50. Bar 52 may be tubular. Alternatively, bar 52 may be solid.

Referring now to FIGS. 4-6, a suspension 114 in accordance with anotherembodiment of the present invention will be described. Suspension 114includes many of the same components found in suspension 14 andtherefore like reference numbers will be used for similar components.Suspension 114 couples steer axle assembly 12 to frame 10. Suspension114 may include mounting brackets 142, leaf springs 44, air springs 46,shock absorbers 48, mounting arms 150, and a torsion bar 52. Althoughonly one side of the vehicle and suspension 114 are illustrated in FIGS.4-6, it should again be understood that like components for suspension114 may be found on the opposite side of the vehicle.

Mounting brackets 142 provide a means for mounting one or moresuspension components of suspension 114 to axle beam 28 for use indampening movements between axle assembly 12 and frame 10. Referring toFIG. 7, brackets 142 are generally rectangular in shape. Each bracket142 may define multiple grooves 154 in an upper face 156 of the platethat extend transverse to the longitudinal direction of the vehicle andsubstantially parallel to the longitudinal direction of axle beam 28.Each groove 154 may terminate at either end in a bore that extendsvertically through bracket 142. Grooves 154 are configured to receiveconventional U-bolts 58 that extend through the bores in bracket 142 andinto corresponding bores on beam 28 to couple bracket 142 to beam 28.Although each bracket contains two grooves 154 each configured toreceive a U-bolt 58, it should be understood that the number of grooves154 and U-bolts 58 may vary. Each bracket 42 may further define a pairof rearwardly extending spaced ears 160, 162 having coaxial apertures.Ears 160, 162 are sized to receive one end of arm 150 with the aperturesin ears 160, 162 receiving a fastener that extends through arm 150. Theupper face 156 of bracket 142 defines a spring seat configured toreceive spring 46 and opposing the spring seat formed in mountingbracket 22.

Leaf springs 44 are provided to dampen movement and vibration betweenframe 10 and steer axle assembly 12. Leaf springs 44 also providelateral support to the steer axle assembly 12 by transferring lateralloads from the axle beam 28 into mounting brackets 20, 24 of frame 10.Springs 44 are conventional in the art. Each spring 44 extendssubstantially parallel to rails 16, 18 in the longitudinal direction ofthe vehicle and is coupled to frame 10 at forward and rearward ends 64,66 and to beam 28 of steer axle assembly 12 intermediate the forward andrearward ends 64, 66. The forward end 64 is pivotally coupled to bracket24 and disposed about a pivot axis between the downwardly extendingspaced ears at the forward end of bracket 24. The rearward end 66 iscoupled to a shackle 167 which is in turn mounted on the pin extendingfrom bracket 20. End 66 is also disposed about a pivot axis. Leaf spring44 is coupled to beam 28 intermediate ends 64, 66 of leaf spring bybracket 142. In particular, leaf spring 44 is disposed between orsandwiched between bracket 142 and beam 28, extending through theU-bolts 58 that couple bracket 142 to beam 28. In the illustratedembodiment, each side of the vehicle again includes a single leaf spring44. As set forth above, the use of a single leaf spring in combinationwith spring 46 on either side of the vehicle is advantageous as comparedto conventional multiple leaf spring suspensions. In particular, theillustrated suspension has a lower vertical spring rate that provides asofter ride for passengers and cargo.

Springs 46 and shock absorbers 48 are provided to dampen movementsbetween steer axle assembly 12 and frame 10. Springs 46 are conventionalin the art and may comprise an air spring. It should be understood,however, that mechanical springs could alternately be used. Springs 46are disposed between axle beam 28 and frame rails 16, 18. In particular,springs 46 are supported on mounting bracket 142 between opposed springseats defined by brackets 22 frame 10 and bracket 142 of suspension 114,respectively. Shock absorbers 48 are also conventional in the art. Shockabsorbers 48 are coupled at a first end to mounting brackets 150 and ata second end to frame rails 16, 18. Shock absorbers 48 may include eyesat each end configured to receive rod or tubes extending outboard fromrails 16, 18 and arm 150.

Arms 150 provide a means for mounting torsion bar 52 to the vehicle.Arms 150 also reduce axle wind-up during braking by transferring some ofthe braking loads into frame 10 that would otherwise travel into leafsprings 44. Each arm 150 is disposed on a rearward side of axle beam 28relative to the direction of vehicle travel. Each arm 150 extendsgenerally parallel to the longitudinal direction of the vehicle. Eacharm 150 is pivotally coupled to beam 28 and frame 10 at its forward andrearward ends 168, 170, respectively, with end 170 coupled to frame 10proximate the rearward end of leaf spring 44 and disposed about a pivotaxis extending substantially parallel to the pivot axis of the rearwardend of leaf spring 44. End 168 of arm 150 is pivotally coupled tomounting bracket 142 of suspension 114 (which is in turn coupled to axlebeam 28) on the rearward side of axle beam 28. In particular, end 168 isreceived between ears 160, 162 of mounting brackets 148. End 170 of arm150 is pivotally coupled to shackle 167 (which is in turn coupled tobracket 20 of frame 10) which defines a pair of forwardly extendingspaced ears configured to receive end 170 of arm 150. Each end 168, 170may include a conventional bushing or other means for enable relativerotation of arm 150 relative to bracket 142 and shackle 167. Ends 168,170 of arm 150 are both located above leaf spring 44 in the illustrateembodiment.

Arm 150 may include multiple members 180, 182. Referring to FIG. 8,member 180 is shown in greater detail. Member 180 may include arelatively straight bar 184 or rod extending between and coupled to twomounting brackets 186, 188 disposed at the ends 168, 170 of arm 150.Bracket 186 may include a bore 190 configured to receive a bushing toallow relative rotation between member 180 and mounting bracket 142 (seeFIGS. 4-6). Bracket 186 also include a pair of spaced ears 192, 194having apertures coaxial with one another and with an aperture formed inbar 184. The spacing between ears 192, 194 and bar 184 is sized so as toreceive one eye of shock absorber 48 (best shown in FIGS. 4-6). Bracket186 also defines an aperture 196 configured to receive a fastener (notshown) by which member 182 is coupled to member 180. Bracket 188 definesa bore 198 configured to receive a bushing to allow relative rotationbetween member 180 and shackle 167. Bracket 188 also defines an aperture200 configured to receive a fastener (not shown) by which member 182 iscoupled to member 180.

Referring again to FIGS. 4-6, member 182 is generally V-shaped in a sideview. Member 182 is rigidly coupled to member 180 at its forward andrearward ends by fasteners (not shown) extending through apertures inmember 182 that are aligned with apertures 196, 200 in brackets 186, 188of member 180. It should be understood, however, that members 180, 182may be formed as a one-piece, unitary construction. Member 182 iscoupled to member 180 at its forward and rearward ends at locationsabove leaf spring 44. Member 182 further defines an aperture 174intermediate ends 168, 170 of arm 150 configured to receive onelongitudinal end of torsion bar 52. Aperture 174 may be disposed belowleaf spring 44. As shown in FIGS. 4-6, member 182 may be widest at itsconnection points to member 180 and at aperture 174 to providesufficient strength to arm 150 while minimizing the weight of arm 150.

Torsion bar 52 is provided to increase the lateral stability and rollstiffness of the vehicle and to reduce axle wind-up during braking. Bar52 is disposed on a forward side of axle beam 28 and extendssubstantially parallel to beam 28, transverse to the longitudinaldirection of the vehicle. Bar 52 extends between and is coupled to arms150 on either side of the vehicle. Bar 52 is received within apertures174 of arms 150. Bar 52 may be tubular. Alternatively, bar 52 may besolid.

Referring now to FIGS. 9-10, shackle 167 will be described in greaterdetail. Shackle 167 is provided to pivotally couple one end of leafspring 44 and one end of arm 150 to frame 10. Shackle 167 couples leafspring 44 and arm 150 in such a manner that the pivot axes of leafspring 44 and arm 150 are substantially parallel to one another. Shackle167 may include a pair of spaced members 202, 204. Each of members 202,204 may be substantially rectangular in shape while defining forwardprojecting spaced ears 206, 208 configured to receive end 170 of arm150. Members 202, 204 may define several pairs of aligned apertures 210,212, 214. Apertures 210 are configured to receive a fastener 216coupling shackle 167 to frame 10. Apertures 212 are configured toreceive a fastener 218 extending through end 66 of leaf spring 44.Finally, apertures 214 are configured to receive a fastener 220extending through end 170 of arm 150. Fasteners 216, 218, 220 maycomprise bolts or pins or other conventional fasteners. Ears 206, 208and apertures 214 may be disposed on one side of a line 222 connectingapertures 210, 212 such that ears 206, 208 project forward and apertures214 are nearer axle beam 28 than apertures 210, 212. Ears 206, 208 andapertures 214 may also be located such that apertures 214 are verticallyabove apertures 212 and vertically below apertures 212.

A suspension 14 or 114 in accordance with the present invention isadvantageous. Arms 50 or 150 reduce axle wind-up during braking bytransferring some of the braking loads into the vehicle frame 10 thatwould otherwise travel into the leaf springs 44. The use of a torsionbar 52 in some embodiments of suspension 14 or 114 also provides lateralstability and roll stiffness to the vehicle and also reduces axlewind-up during braking and the mounting arrangement for torsion bar 52enables these benefits to be achieved without hindering verticalmovement of the axle and creating undue stress on other suspensioncomponents.

While the invention has been shown and described with reference to oneor more particular embodiments thereof, it will be understood by thoseof skill in the art that various changes and modifications can be madewithout departing from the spirit and scope of the invention.

1. A suspension for coupling a steer axle assembly to a vehicle framehaving first and second longitudinal frame rails, comprising: a firstleaf spring coupled to said vehicle frame at first and second ends andto an axle beam of said steer axle assembly intermediate said first andsecond ends; a first arm pivotally coupled to said axle beam at a firstend and to said vehicle frame at a second end proximate one of saidfirst and second ends of said first leaf spring; a second leaf springcoupled to said vehicle frame at first and second ends and to said axlebeam of said steer axle assembly intermediate said first and secondends, said second leaf spring disposed on an opposite side of saidvehicle frame from said first leaf spring; and, a second arm pivotallycoupled to said axle beam at a first end and to said vehicle frame at asecond end proximate one of said first and second ends of said secondleaf spring
 2. The suspension of claim 1, further comprising a torsionbar extending between and coupled to said first and second arms.
 3. Thesuspension of claim 2 wherein said torsion bar is tubular.
 4. Thesuspension of claim 1, further comprising first and second mountingbrackets coupled to said axle beam, said first leaf spring disposedbetween said first mounting bracket and said axle beam and said secondleaf spring disposed between said second mounting bracket and said axlebeam.
 5. The suspension of claim 4, further comprising first and secondsprings disposed between said axle beam and said first and secondlongitudinal frame rails, said first and second springs supported onsaid first and second mounting brackets, respectively.
 6. The suspensionof claim 1, further comprising first and second springs disposed betweensaid axle beam and said first and second longitudinal frame rails. 7.The suspension of claim 1 wherein said first and second ends of saidfirst and second arms are disposed below said first and second leafsprings, respectively.
 8. The suspension of claim 1 wherein said firstand second ends of said first and second arms are disposed above saidfirst and second leaf springs, respectively.
 9. The suspension of claim1, further comprising: a first shackle coupled to said vehicle frame,one of said first and second ends of said first leaf spring pivotallycoupled to said first shackle and said second end of said first armpivotally coupled to said first shackle; and, a second shackle coupledto said vehicle frame, one of said first and second ends of said secondleaf spring pivotally coupled to said second shackle and said second endof said second arm pivotally coupled to said second shackle.
 10. Asuspension for coupling a steer axle assembly to a vehicle frame havingfirst and second longitudinal frame rails, comprising: a first leafspring coupled to said vehicle frame at a forward end and at a rearwardend and to an axle beam of said steer axle assembly intermediate saidforward and rearward ends; a first arm pivotally coupled to said axlebeam at a rearward end and to said vehicle frame at a forward endproximate said forward end of said first leaf spring, said forward andrearward ends of said first arm disposed below said first leaf spring; asecond leaf spring coupled to said vehicle frame at a forward end at arearward end and to said axle beam of said steer axle assemblyintermediate said forward and rearward ends, said second leaf springdisposed on an opposite side of said vehicle frame from said first leafspring; and, a second arm pivotally coupled to said axle beam at arearward end and to said vehicle frame at a forward end proximate saidforward end of said second leaf spring, said forward and rearward endsof said second arm disposed below said second leaf spring
 11. Thesuspension of claim 10, further comprising a torsion bar extendingbetween and coupled to said first and second arms.
 12. The suspension ofclaim 11 wherein said first arm defines an aperture configured toreceive said torsion bar.
 13. The suspension of claim 11 wherein saidtorsion bar is tubular.
 14. The suspension of claim 10 wherein saidforward end of said first arm is vertically higher than said rearwardend of said first arm.
 15. The suspension of claim 10, furthercomprising a first mounting bracket coupled to said axle beam, saidfirst leaf spring disposed between said first mounting bracket and saidaxle beam.
 16. The suspension of claim 15, further comprising a firstshock absorber, said first shock absorber coupled at a first end to saidfirst mounting bracket and at a second end to said first longitudinalframe rail.
 17. The suspension of claim 10, further comprising first andsecond springs disposed between said axle beam and said first and secondlongitudinal frame rails.
 18. A suspension for coupling a steer axleassembly to a vehicle frame having first and second longitudinal framerails, comprising: a first leaf spring coupled to said vehicle frame ata forward end and at a rearward end and to an axle beam of said steeraxle assembly intermediate said forward and rearward ends; a first armpivotally coupled to said axle beam at a forward end and to said vehicleframe at a rearward end proximate said rearward end of said first leafspring, said forward and rearward ends of said first arm disposed abovesaid first leaf spring; a second leaf spring coupled to said vehicleframe at a forward end at a rearward end and to said axle beam of saidsteer axle assembly intermediate said forward and rearward ends, saidsecond leaf spring disposed on an opposite side of said vehicle framefrom said first leaf spring; and, a second arm pivotally coupled to saidaxle beam at a forward end and to said vehicle frame at a rearward endproximate said rearward end of said second leaf spring, said forward andrearward ends of said second arm disposed above said second leaf spring.19. The suspension of claim 18, further comprising a torsion barextending between and coupled to said first and second arms.
 20. Thesuspension of claim 19 wherein said first arm defines an apertureconfigured to receive said torsion bar.
 21. The suspension of claim 19wherein said torsion bar is tubular.
 22. The suspension of claim 19wherein said first arm includes a first member disposed above said firstleaf spring and a second member having first and second ends rigidlycoupled to said first member at locations above said first leaf springand defining an aperture intermediate said first and second ends andbelow said first leaf spring, said aperture configured to receive saidtorsion bar.
 23. The suspension of claim 18, further comprising a firstmounting bracket coupled to said axle beam, said first leaf springdisposed between said first mounting bracket and said axle beam.
 24. Thesuspension of claim 23 wherein said first arm is pivotally coupled tosaid first mounting bracket.
 25. The suspension of claim 18, furthercomprising a first shock absorber, said first shock absorber coupled ata first end to said first arm and at a second end to said firstlongitudinal frame rail.
 26. The suspension of claim 18, furthercomprising first and second springs disposed between said axle beam andsaid first and second longitudinal frame rails.
 27. The suspension ofclaim 18, further comprising: a first shackle coupled to said vehicleframe, one of said first and second ends of said first leaf springpivotally coupled to said first shackle and said second end of saidfirst arm pivotally coupled to said first shackle; and, a second shacklecoupled to said vehicle frame, one of said first and second ends of saidsecond leaf spring pivotally coupled to said second shackle and saidsecond end of said second arm pivotally coupled to said second shackle.